If it's one of mine, the Internet object either points to a folder, or opens the internet menu. If the latter is the case, just browse to FF and drag it over to the internet menu and drop it there. This will create a FF shortcut in the menu. You must be in builder mode to do this. Once you have all your shortcuts in each menu, save the theme and it saves your changes.
If it is the folder shortcut, and you have no such folder, then be sure you check the box that says file shortcut, then click browse to find the needed target. If you need more help, email me at PuterDudeJim@aol.com.